JP7137363B2 - Exposure method, exposure apparatus, article manufacturing method and measurement method - Google Patents

Description

The present invention relates to an exposure method, an exposure apparatus, an article manufacturing method, and a measurement method.

2. Description of the Related Art An exposure apparatus having a projection optical system for projecting a pattern of an original onto a substrate is used when manufacturing devices such as semiconductor devices such as ICs and LSIs, liquid crystal display devices, imaging devices such as CCDs, and magnetic heads. In order to accurately transfer the pattern of the original onto the substrate in the exposure apparatus, it is necessary to determine a reference plane that is less affected by the surface shape of the substrate, and to position this reference plane on the imaging plane of the projection optical system with high accuracy. is important.

A step-and-scan exposure apparatus (scanner) exposes a substrate held on a substrate stage while driving the substrate stage holding the substrate in a scanning direction. At that time, the distance between the imaging plane of the projection optical system and the reference plane of the substrate is measured by a focus sensor, and based on the measurement result, the substrate stage is driven in a direction orthogonal to the imaging plane to move the reference plane. Follow-up driving is performed to sequentially align the . In such follow-up driving, the distance between the imaging plane of the projection optical system and the reference plane of the substrate is measured in advance by a focus sensor (pre-reading sensor) in front of the exposure position while the substrate stage is being scanned ( read ahead) is required.

Follow-up driving basically assumes that the surface shape of the substrate is flat. On the other hand, substrates in recent years are often composed of multilayer patterns. Since the surface (base) of such a substrate has a stepped structure including many irregularities, if the substrate stage is made to follow such irregularities, a follow-up error occurs due to abrupt fluctuations in the amount of movement of the substrate stage, resulting in poor focus accuracy. decreases.

Therefore, in order to apply follow-up driving to a substrate having a stepped structure, it is necessary to deal with unevenness of the surface of the substrate. Therefore, in order to improve the follow-up drive for a substrate with a stepped structure, a technology has been proposed to suppress sharp fluctuations in the amount of movement of the substrate stage by managing the measurement offset from the reference surface caused by unevenness for each measurement point. (See Patent Document 1).

JP-A-9-45608

However, since the exposure apparatus generally uses an oblique-incidence focus sensor, when the distance from the focus sensor to the substrate (the position in the focus direction) changes, the measurement point shifts in the lateral direction. . Therefore, if a measurement offset is obtained at a position in the focus direction as in the conventional technique, when the position in the focus direction changes, a measurement offset from the reference plane caused by unevenness will occur due to the shift of the measurement point. It is not reflected correctly, and a tracking error occurs. As described above, the prior art does not provide effective means for suppressing deterioration in focus accuracy due to the influence of the shift of the measurement point.

SUMMARY OF THE INVENTION It is an exemplary object of the present invention to provide an exposure method that is advantageous in terms of focus accuracy.

In order to achieve the above object, an exposure method as one aspect of the present invention is an exposure method for exposing a substrate while moving an original and a substrate in a scanning direction, wherein a plurality of exposures in the height direction of the substrate are performed. The substrate is positioned at each of the positions, and light is obliquely incident on each of the plurality of measurement points on the substrate while moving the substrate in the scanning direction for each of the plurality of positions, thereby measuring each measurement point. A first step of acquiring a first measured value of the position in the height direction by a measuring unit; and based on the first measured value of each measurement point at each of the plurality of positions acquired in the first step, a second step of determining the surface shape of the substrate to identify the positions of the unevenness existing on the substrate; light obliquely incident on each of the plurality of measurement points while moving, and based on a second measurement value of the position of each measurement point in the height direction obtained by the measurement unit ; and a third step of driving the substrate so that the position of is the target position.

Further objects or other aspects of the present invention will be made clear by preferred embodiments described below with reference to the accompanying drawings.

According to the present invention, for example, it is possible to provide an exposure method that is advantageous in terms of focus accuracy.

1 is a schematic diagram showing the configuration of an exposure apparatus as one aspect of the present invention; FIG. 4 is a diagram showing a positional relationship between a substrate and measurement light from a focus measurement unit; FIG. FIG. 3 is a diagram showing the positional relationship between the imaging plane of the projection optical system, the reference plane of the substrate, and the measurement light; FIG. 4 is a diagram for explaining shift of measurement points on a substrate; FIG. 3 is a diagram showing the positional relationship between the imaging plane of the projection optical system, the reference plane of the substrate, and the measurement light; It is a figure which shows an example of the measurement point on a board|substrate. FIG. 10 is a diagram for explaining correction of measured values at each measuring point on a substrate; FIG. 3 is a diagram showing the relationship between each measurement point on a substrate and the surface of the substrate; FIG. 10 is a diagram for explaining correction of the target position of the substrate stage; 2 is a flow chart for explaining the operation of the exposure apparatus shown in FIG. 1;

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. In addition, in each figure, the same reference numerals are given to the same members, and redundant explanations are omitted.

FIG. 1 is a schematic diagram showing the configuration of an exposure apparatus 100 as one aspect of the present invention. The exposure apparatus 100 is a step-and-scan exposure apparatus (scanner) that exposes the substrate 5 (scanning exposure) while moving the original 1 and the substrate 5 to transfer the pattern of the original 1 onto the substrate. . As shown in FIG. 1, the exposure apparatus 100 includes an original stage 2, a first measurement section 3, a projection optical system 4, a substrate holder 6, a substrate stage 7, a second measurement section 8, a third measurement It has a unit 9 , a control unit 10 and a focus measurement unit 30 .

Further, in this embodiment, directions are indicated using an XYZ coordinate system in which the XY plane is the direction parallel to the surface of the substrate 5 . The directions parallel to the X, Y, and Z axes in the XYZ coordinate system are defined as the X direction, the Y direction, and the Z direction, respectively. , θY and θZ.

The original stage 2 holds the original 1 on which a fine pattern to be transferred to the substrate 5 is formed. The original stage 2 includes, for example, a suction unit (not shown) for sucking the original 1, and holds the original 1 by vacuum-sucking the original 1 with the suction unit. The original stage 2 includes an actuator (not shown) for moving in the Y direction, and a linear motor is mainly used as such actuator.

The first measuring unit 3 includes, for example, an interferometer and an optical linear encoder, and measures the position of the original stage 2 in the Y direction. In addition, in order to enable tilt control of the original stage 2, the first measurement unit 3 measures at least three positions on a measurement surface provided on the side surface of the original stage 2 to determine the tilt component of the original stage 2. get. The position of the original stage 2 measured by the first measuring section 3 is input to the control section 10 .

The original 1 held on the original stage 2 is illuminated by an illumination optical system (not shown). An image of the pattern of the original 1 is reduced via the projection optical system 4 and transferred to the substrate 5 .

The substrate stage 7 holds the substrate 5 via the substrate holder 6 . The substrate stage 7 includes a suction portion (not shown) for suctioning (vacuum-sucking) the substrate 5 and the substrate holder 6 . In order to reduce unevenness of the substrate 5, the substrate holder 6 is processed flat on both the surface on the substrate stage side and the surface on the substrate side. Further, the substrate holder 6 is made of a material with high temperature stability such as ceramics in order to reduce deformation due to temperature changes. The substrate stage 7 includes actuators for moving in the X, Y and Z directions, and linear motors and voice coil motors are used as such actuators.

A second measuring unit 8 measures the position of the substrate stage 7 in the X direction and the Y direction. A third measuring unit 9 measures the position of the substrate stage 7 in the Z direction. Also, as with the original stage 2 , the second measurement unit 8 measures at least three positions on the measurement surface provided on the side surface of the substrate stage 7 in order to enable tilt control of the substrate stage 7 . The positions of the substrate stage 7 measured by the second measuring section 8 and the third measuring section 9 are input to the control section 10 .

The control unit 10 is composed of a computer including a CPU, a memory, etc., and operates the exposure apparatus 100 by comprehensively controlling each unit of the exposure apparatus 100 according to a program stored in the storage unit. The controller 10 controls the original stage 2 and the substrate stage 7 in order to transfer the pattern to each of a plurality of shot areas on the substrate. In addition, in order to accurately form an image of the pattern, the control unit 10 receives from the focus measurement unit 30 the distance between the imaging plane of the projection optical system 4 and the substrate 5, the tilt, and the reference plane of the substrate 5 during the scanning exposure. Get information about Then, the control unit 10 drives the substrate stage 7 in the Z direction to perform follow-up driving for sequentially aligning the reference plane of the substrate 5 with the imaging plane of the projection optical system 4 .

The focus measurement unit 30 includes a light source 11, a projection lens 12, reflecting mirrors 13 and 14, a light receiving lens 15, a cylindrical lens 16, a line sensor 17, and a calculation unit 18. Light from the light source 11 is projected onto a slit (not shown). Light from the slits (projection marks formed by the slits) is incident (obliquely incident) on a plurality of positions on the substrate 5 via the projection lens 12 and the reflection mirror 13 at a constant angle. The light reflected by the substrate 5 enters the cylindrical lens 16 via the reflecting mirror 14 and the light receiving lens 15 . The projection lens 12 and the light receiving lens 15 are composed of telecentric lenses. The light incident on the cylindrical lens 16 is integrated one-dimensionally, and the line sensor 17 acquires light intensity information at each pixel position. The line sensor 17 is composed of a CCD, CMOS sensor, or the like, and detects light reflected by the substrate 5 . A plurality of line sensors 17 are arranged according to the number of projection marks formed by slits. The calculation unit 18 calculates the distance between the focus measurement unit 30 and the substrate 5, the inclination, and the reference plane of the substrate 5 based on the information on the light intensity acquired by the line sensor 17, and inputs them to the control unit 10. do.

FIG. 2 is a diagram showing the positional relationship between the substrate 5 and the measurement light of the focus measurement unit 30 (the light reflected by the reflection mirror 13 and incident on the substrate 5). The exposure apparatus 100 exposes the substrate 5 while scanning (driving) the substrate 5 back and forth in the scanning direction (Y direction). Therefore, the focus measurement unit 30 has measurement light SC for measuring the focus at the exposure position (exposure area) and measurement light SF for measuring (pre-reading) the focus at a position distant from the exposure position in the scanning direction. and SB are made incident on the substrate 5 . Here, the focus includes the position of the substrate 5 in the height direction (Z direction), for example, the distance between the imaging plane of the projection optical system 4 and the reference plane of the substrate 5 .

3A and 3B are diagrams showing the positional relationship between the imaging plane of the projection optical system 4, the reference plane of the substrate 5, and the measurement beams SC, SF, and SB. FIGS. 3A and 3B show the state during exposure scanning, in which the substrate stage 7 is scanned in the +Y direction (the direction perpendicular to the height direction (Z direction) of the substrate 5), and the pre-reading measurement is It is assumed that measurement light SF is used.

As shown in FIG. 3A, while the substrate stage 7 is scanning, the distance ΔZ between the imaging plane of the projection optical system 4 and the reference plane of the substrate 5 is measured by the measurement light SF. Then, as shown in FIG. 3B, before the measurement point MP on the substrate measured by the measurement light SF reaches the exposure position C, the substrate stage 7 is driven by ΔZ in the +Z direction so that the measurement point MP When the exposure position C is reached, exposure is started. At the same time as the measurement point MP on the substrate is exposed, the focus error at the exposure position C is measured by the measurement light SC. Scanning exposure is made possible by continuously performing these operations while changing the position of the measurement point on the substrate.

Since the focus measurement unit 30 is an oblique incidence type focus sensor, as shown in FIG. 4, when the distance between the focus measurement unit 30 and the substrate 5 changes, the measurement point on the substrate shifts in the X direction. . For example, when the measurement light is incident on the substrate 5 from the +X direction at an incident angle θ, if the position of the substrate 5 changes by ΔZ in the −Z direction, the measurement point MP is shifted in the −X direction as indicated by the measurement point MP′. ΔX (=ΔZ/tan θ).

5(a) and 5(b) are diagrams for explaining in detail the shift of the measurement point on the substrate. The positional relationship with lights SC, SF and SB is shown. 5(a) and 5(b) show the state during scanning exposure, it is assumed that the substrate stage 7 is scanned in the +Y direction and pre-read measurement is performed with the measurement light SF.

As shown in FIG. 5A, when the distance between the imaging plane of the projection optical system 4 and the reference plane is ΔZ1, and when the distance between the imaging plane of the projection optical system 4 and the reference plane is The measurement points on the substrate are different between the case of ΔZ2 and the case of X(ΔZ1) and X(ΔZ2), respectively. Now, consider obtaining a measurement offset from the reference plane caused by the unevenness (step) 19 of the substrate 5 as in the prior art. For example, assume that the measurement offset is obtained from the distance ΔZ2 between the imaging plane of the projection optical system 4 and the reference plane. In this case, if follow-up driving is performed from the distance ΔZ1 between the imaging plane of the projection optical system 4 and the reference plane, the measurement offset ΔZ′ due to the unevenness 19 of the substrate 5 will not be reflected, as shown in FIG. In addition, an error occurs in the driving amount ΔZ of the substrate stage 7 . Alternatively, the measurement offset may be obtained from the distance ΔZ1 between the imaging plane of the projection optical system 4 and the reference plane, and follow-up driving may be performed from the distance ΔZ2 between the imaging plane of the projection optical system 4 and the reference plane. In addition, an error occurs in the driving amount ΔZ of the substrate stage 7 .

Therefore, in the present embodiment, even if the substrate 5 has unevenness 19, highly accurate follow-up driving is realized during scanning exposure, and a technique advantageous in terms of focus accuracy is provided.

<First embodiment>
FIG. 6A is a diagram showing measurement points (white dots) on the substrate measured by the focus measurement unit 30 at each of a plurality of positions on the substrate stage 7 (substrate 5) in the Z direction. FIG. 6A shows the measurement points on the substrate corresponding to the measurement light SF among the measurement points (black dots) on the substrate corresponding to the measurement light SF, SC and SB shown in FIG.

In this embodiment, before scanning exposure is started, first, the substrate stage 7 (substrate 5) is driven so that the substrate stage 7 (substrate 5) is positioned at the Z position (position in the Z direction) Z(0). Then, while scanning the substrate stage 7 in the +Y direction, the focus is measured at each measurement point on the substrate. At this time, the measurement points on the substrate at the Z position Z(0) are (Y(0), Z(0)), (Y(1), Z(0)), as shown in FIG. , . . . , (Y(4), Z(0)). In addition, the focus measurement unit 30 also obtains measurement values FZ (FZ (Y(0), Z(0)), FZ (Y(1), Z(0)), . . . , FZ( Y(4), Z(0))).

Next, the substrate stage 7 is driven so that the substrate stage 7 is positioned at the Z position Z(1). Then, while scanning the substrate stage 7 in the +Y direction, the focus is measured at each measurement point on the substrate. At this time, the measurement points on the substrate at the Z position Z(1) are (Y(0), Z(1)), (Y(1), Z(1)), as shown in FIG. , . . . , (Y(4), Z(1)). In addition, the focus measurement unit 30 also obtains measurement values FZ (FZ (Y(0), Z(1)), FZ (Y(1), Z(1)), . . . , FZ( Y(4), Z(1))) is obtained.

Similarly, the substrate stage 7 is driven so that the substrate stage 7 is positioned at the Z position Z(2). Then, while scanning the substrate stage 7 in the +Y direction, the focus is measured at each measurement point on the substrate. At this time, the measurement points on the substrate at the Z position Z(2) are (Y(0), Z(2)), (Y(1), Z(2)), as shown in FIG. , . . . , (Y(4), Z(2)). In addition, the focus measurement unit 30 also obtains measurement values FZ (FZ (Y(0), Z(2)), FZ (Y(1), Z(2)), . . . , FZ( Y(4), Z(2))) is obtained.

By changing the Z position of the substrate stage 7 (substrate 5) in this way, the measurement point on the substrate shifts in the X direction. Therefore, by positioning the substrate 5 at a plurality of Z positions and obtaining the measured values FZ at each measurement point while moving the substrate in the Y direction for each of the plurality of Z positions, the substrate with the Z position as a reference can be obtained. The position of the unevenness 19 can be specified by obtaining the surface shape of 5 .

After acquiring the measured value FZ (first measured value) at each measuring point on the substrate for each Z position, the measured value FZ and the Z position of the substrate stage 7 (substrate 5) are calculated for each measuring point as shown below. ΔFZ (measurement offset) is calculated.
ΔFZ((Y(0),Z(0))=FZ((Y(0),Z(0))−Z(0)
ΔFZ((Y(1),Z(0))=FZ((Y(1),Z(0))−Z(0)
・・・
ΔFZ((Y(4),Z(0))=FZ((Y(4),Z(0))−Z(0)
ΔFZ((Y(0),Z(1))=FZ((Y(0),Z(1))−Z(1)
ΔFZ((Y(1),Z(1))=FZ((Y(1),Z(1))−Z(1)
・・・
ΔFZ((Y(4),Z(1))=FZ((Y(4),Z(1))−Z(1)
ΔFZ((Y(0),Z(2))=FZ((Y(0),Z(2))−Z(2)
ΔFZ((Y(1),Z(2))=FZ((Y(1),Z(2))−Z(2)
・・・
ΔFZ((Y(4),Z(2))=FZ((Y(4),Z(2))−Z(2)
7A is a diagram showing the relationship between the measured value FZ of each measurement point on the substrate measured by the focus measurement unit 30 and the Z position of the substrate stage 7 measured by the third measurement unit 9. FIG. . In FIG. 7A , the vertical axis indicates the measured value FZ of each measurement point on the substrate, and the horizontal axis indicates the Z position of the substrate stage 7 . Referring to FIG. 7A, at the measurement point where the substrate 5 has a flat shape, the measured value FZ and the Z position change linearly. On the other hand, at the measurement point (Y(2), Z(2)) located on the unevenness 19 existing on the substrate 5, the difference between the measured value FZ(Y(2), Z(2)) and the Z position Z(2) is A difference ΔFZ(Y(2), Z(2)) is generated between them.

FIG. 7B shows the correction of the measured value FZ at each measurement point on the substrate when it is assumed that the unevenness 19 existing on the substrate 5 is measured at the Y position (position in the Y direction) Y(2) during scanning exposure. is a diagram conceptually showing the . After starting scanning exposure, the measured value FZ at each measuring point is corrected based on the measured value FZ (second measured value) obtained by measuring the focus at each measuring point on the substrate and the difference ΔFZ.

For example, when the substrate stage 7 is positioned at Y positions Y(0) and Y(1) and the focus is measured, the Z position of the substrate stage 7 is positioned near Z(0). think. In this case, as shown below, the difference ΔFZ at each measurement point (Y(0), Z(0)), (Y(1), Z(0)) is is obtained as the corrected measured value FZ'.
FZ'(Y(0),Z(0))=FZ(Y(0),Z(0))-ΔFZ(Y(0),Z(0))
FZ′(Y(1),Z(0))=FZ(Y(1),Z(0))−ΔFZ(Y(1),Z(0))
Next, consider a case where the Z position of the substrate stage 7 is positioned near Z(2) when the focus is measured with the substrate stage 7 positioned at the Y position Y(2). In this case, as shown below, the measured value FZ is corrected by the difference ΔFZ at the measurement points (Y(2), Z(2)) to obtain the corrected measured value FZ′.
FZ′(Y(2),Z(2))=FZ(Y(2),Z(2))−ΔFZ(Y(2),Z(2))
Although the measured values FZ(Y(2), Z(2)) include measurement errors caused by the unevenness 19 present on the substrate 5, the difference ΔFZ(Y(2), Z(2)) is subtracted. This eliminates the measurement error.

Next, when the substrate stage 7 is positioned at each of the Y positions Y(3) and Y(4) and the focus is measured, the Z position of the substrate stage 7 is positioned near Z(0). think of. In this case, as shown below, the difference ΔFZ at each measurement point (Y(3), Z(0)), (Y(4), Z(0)) is is obtained as the corrected measured value FZ'.
FZ′(Y(3),Z(0))=FZ(Y(3),Z(0))−ΔFZ(Y(3),Z(0))
FZ′(Y(4),Z(0))=FZ(Y(4),Z(0))−ΔFZ(Y(4),Z(0))
Accordingly, the corrected measurement value FZ' at each measurement point on the substrate is expressed as follows.
FZ'(Y(0),Z(0))=FZ(Y(0),Z(0))-ΔFZ(Y(0),Z(0))
FZ′(Y(1),Z(0))=FZ(Y(1),Z(0))−ΔFZ(Y(1),Z(0))
FZ′(Y(2),Z(2))=FZ(Y(2),Z(2))−ΔFZ(Y(2),Z(2))
FZ′(Y(3),Z(0))=FZ(Y(3),Z(0))−ΔFZ(Y(3),Z(0))
FZ′(Y(4),Z(0))=FZ(Y(4),Z(0))−ΔFZ(Y(4),Z(0))
According to this embodiment, even if the measurement point on the substrate shifts to the unevenness 19 during scanning exposure, the measurement error can be eliminated by correcting the measurement value FZ with the difference ΔFZ obtained before scanning exposure. Such correction is performed for each measurement point on the substrate on which each of the measurement beams SF, SC, and SB shown in FIG. 2 is incident. Therefore, in the exposure apparatus 100, when the substrate 5 is scanned and exposed, the follow-up drive for sequentially aligning the substrate 5 (the reference plane) with the imaging plane of the projection optical system 4 by driving the substrate stage 7 in the Z direction is high. Since it is possible to perform the focusing with accuracy, it is possible to suppress deterioration of the focusing accuracy.

<Second embodiment>
In this embodiment, a case will be described in which the target position of the substrate stage 7 during scanning exposure is corrected based on the difference ΔFZ obtained before scanning exposure. In order to determine the target position of the substrate stage 7, it is necessary to obtain the surface shape of the substrate 5 from the measured values FZ at each measurement point on the substrate.

When obtaining the surface shape of the substrate 5, the method of least squares is generally used. FIG. 8 is a diagram showing the relationship between each measurement point on the substrate and the surface (surface shape) of the substrate 5. As shown in FIG. In FIG. 8, the surface of the substrate 5 is assumed to be a first-order approximation surface. Assuming that each measurement point on the substrate is (X0, Y0, Z0), (X1, Y1, Z1), (X2, Y2, Z2), the approximate surface is the distance between the surface (S=ax+by+c) and each measurement point It is obtained by determining the coefficients (a, b, c) that minimize Δz0, Δz1, and Δz2.

FIG. 9A is a diagram showing measurement points S(0), S(1), and S(2) by the measurement light SF shown in FIG. As described above, the substrate stage 7 (substrate) 5 is driven so that the substrate stage 7 (substrate) 5 is positioned at each of Z positions Z(0), Z(1) and Z(2) before scanning exposure is started. . Then, at each Z position, the focus is measured at each of Y positions Y(0), Y(1), Y(2), and Y(3) while scanning the substrate stage 7 in the +Y direction. Next, from the measured values of measurement points (Y(0), Z(0)), (Y(1), Z(1)), . . . (Y(4), Z(2)) on the substrate A surface shape 20 of the substrate 5 is obtained.

FIG. 9B shows the first-order approximation plane at the Y position Y(2), the measurement points S(0), S(1), and S(2), and the amount of drive of the substrate stage 7 in the Z direction. is a diagram showing the relationship of Let S be the approximate surface of the substrate 5 obtained from the measurement points other than the measurement points (Y(2), Z(2)). Since the approximation plane S is not affected by the irregularities 19 existing on the substrate 5, it is used as the reference plane of the substrate 5 here. Referring to FIG. 9B, the drive amount of the substrate stage 7 is the difference ΔZo between the imaging plane of the projection optical system 4 and the reference plane of the substrate 5. During scanning exposure, the substrate stage 7 is moved in the +Z direction. Drive by ΔZo.

On the other hand, the measurement point (Y(2), Z(2)) is affected by the unevenness 19 existing on the substrate 5, so the difference between the measurement value at the measurement point S(0) and the reference surface of the substrate 5 is ΔFZ(Y(2), Z(2)) is generated, and the approximate plane becomes an approximate plane S' including the tilt component θ. Here, the driving amount of the substrate stage 7 at the Y position Y(2) is the difference ΔZo between the imaging plane of the projection optical system 4 and the reference plane of the substrate 5 and the difference ΔFZ' (Y(2), Z(2) ) is added.

FIG. 9(c) is a diagram conceptually showing the correction of the target position of the substrate stage 7 to follow the imaging plane of the projection optical system 4. As shown in FIG. Assuming that the target position of the substrate stage 7 is TZ, the target position TZ' after correction is obtained by subtracting the difference ΔFZ' from the target position TZ at each measurement point.

For example, when the Z position of the substrate stage 7 is Z(0), the following target position TZ of the substrate stage 7 is obtained based on the measurement value obtained by measuring the focus at the Z position Z(0). 'determine.
TZ'(Y(0),Z(0))=TZ(Y(0))-ΔFZ'(Y(0),Z(0))
TZ'(Y(1), Z(0))=TZ(Y(1))-ΔFZ'(Y(1), Z(0))
TZ'(Y(2), Z(0))=TZ(Y(2))-ΔFZ'(Y(2), Z(0))
TZ'(Y(3),Z(0))=TZ(Y(3))-ΔFZ'(Y(3),Z(0))
TZ'(Y(4),Z(0))=TZ(Y(4))-ΔFZ'(Y(4),Z(0))
When the surface shape 20 of the substrate 5 is flat, the difference ΔFZ′ becomes zero. It matches the position TZ'.

The same applies to the case where the Z position of the substrate stage 7 is Z(1). On the other hand, when the Z position of the substrate stage 7 is Z(2), the target position TZ' of the substrate stage 7 is as shown below.
TZ'(Y(0),Z(2))=TZ(Y(0))-ΔFZ'(Y(0),Z(2))
TZ'(Y(1), Z(2)=TZ(Y(1))-ΔFZ'(Y(1), Z(2))
TZ'(Y(2), Z(2))=TZ(Y(2))-ΔFZ'(Y(2), Z(2))
TZ'(Y(3), Z(2))=TZ(Y(3))-ΔFZ'(Y(3), Z(2))
TZ'(Y(4), Z(2))=TZ(Y(4))-ΔFZ'(Y(4), Z(2))
As described above, at the measurement points (Y(2), Z(2)) on the substrate, an error occurs in the driving amount of the substrate stage 7 due to the unevenness 19 existing on the substrate 5. The error can be removed by correcting the target position with the obtained difference ΔFZ′ (Y(2), Z(2)). Therefore, in the exposure apparatus 100, when the substrate 5 is scanned and exposed, the follow-up drive for sequentially aligning the substrate 5 (the reference plane) with the imaging plane of the projection optical system 4 by driving the substrate stage 7 in the Z direction is high. Since it is possible to perform the focusing with accuracy, it is possible to suppress deterioration of the focusing accuracy. Although the correction of the target position of the substrate stage 7 in the Z direction has been described in this embodiment, it is also applicable to the correction of the target position of the tilt of the substrate stage 7 .

Hereinafter, with reference to FIG. 10, the operation of exposure apparatus 100, more specifically, the operation from loading of substrate 5 to completion of scanning exposure will be described. In the exposure apparatus 100, before scanning exposure is started, a measurement offset is determined by measuring focus while scanning the substrate 5 for each of a plurality of positions in the Z direction.

In S<b>1002 , the substrate 5 is loaded into the exposure apparatus 100 and held on the substrate stage 7 . In S1004, a measurement point on the substrate to be measured by the focus measurement unit 30 is set. Specifically, a combination of a Y position (Y(0), ..., Y(n)) and a Z position (Z(0), ..., Z(m)) as measurement points on the substrate set.

In S1006, as described above, while scanning the substrate stage 7, the focus measurement unit 30 measures the focus at each measurement point on the substrate set in S1004. Thereby, the measured value FZ of each measuring point on the substrate is obtained.

In S1008, the reference plane of the substrate 5 is generated based on the measured value FZ obtained in S1006. In this embodiment, as described above, the reference plane of the substrate 5 is generated based on the measured values of each measurement point at the Z position near the imaging plane of the projection optical system 4 . In S1010, as described above, the difference ΔFZ between the measured value FZ obtained in S1006 and the Z position of the substrate stage 7 is obtained for each measurement point on the substrate.

In S1012, scanning exposure is started. In the scanning exposure, while scanning the substrate stage 7 in the scanning direction, the focus measurement unit 30 measures the focus before each measurement point on the substrate reaches the exposure position to obtain a measurement value. Then, the substrate stage 7 is driven so that the Z position of the substrate stage 7 (substrate 5) is positioned at the target position by the time each measurement point on the substrate reaches the exposure position (that is, the reference plane of the substrate 5 is Follow-up driving is carried out so as to sequentially match the imaging plane of the projection optical system 4).

In S1014, neighboring points Y(k1) and Z(k2) are determined for the current Y position and Z position of the substrate stage 7 during scanning exposure. In this embodiment, the neighboring points Y(k1) and Z(k2) are determined, but instead of deciding the neighboring points Y(k1) and Z(k2), Y Position and Z position may be obtained.

In S1016, follow-up driving of the substrate stage 7 is performed while correcting the measured value FZ obtained from the focus measuring unit 30 during scanning exposure with the difference ΔFZ. Specifically, among the differences ΔFZ obtained in S1010, the differences ΔFZ (Y(k1), Z(k2)) corresponding to the neighboring points Y(k1) and Z(k2) determined in S1014 are selected. Then, as described above, the substrate stage 7 is driven to follow while correcting the measured value FZ (Y(k1), Z(k2)) with the difference ΔFZ (Y(k1), Z(k2)).

In S1018, it is determined whether the scanning exposure of the substrate 5 has been completed. If the scanning exposure of the substrate 5 has been completed, the process proceeds to S1020. On the other hand, if the scanning exposure for the substrate 5 has not ended, the process proceeds to S1014 to continue the scanning exposure.

In S1020, it is determined whether all the substrates 5 have been loaded into the exposure apparatus 100 or not. When all the substrates 5 have been loaded into the exposure apparatus 100, the operation ends. On the other hand, if all the substrates 5 have not been loaded into the exposure apparatus 100, the process proceeds to S1022.

In S1022, the next substrate 5 is loaded into the exposure apparatus 100, the substrate stage 7 holds the substrate 5, and the process proceeds to S1012 to start scanning exposure. When scanning and exposing a series of substrates (for example, substrates in one lot) on which the same underlying treatment has been performed, it is considered that substrate-to-substrate variation in substrates is small. Therefore, in this embodiment, the difference ΔFZ is obtained for the first substrate (for example, the first substrate in the lot) among a series of substrates, and the difference ΔFZ obtained for the first substrate is obtained for the substrates other than the first substrate. is used to correct the measurement. In this case, the processing time can be shortened compared to the case where the focus is measured for all substrates and the difference ΔFZ is obtained. However, even if a series of substrates are subjected to the same surface treatment, the focus may be measured for all substrates to obtain the difference ΔFZ (NO in S1020 may be shifted to S1004). ).

As for the measurement points on the substrate, it is preferable to set the positions and the number of measurement points in consideration of the time required for processing and the influence of accuracy. Further, in order to control the follow-up drive of the substrate stage 7 with higher accuracy, it is also possible to obtain the interpolation by using the position of each measurement point and the difference ΔFZ to perform polynomial interpolation of the first order or the second order or higher. be. Also, the number of drivable axes of the substrate stage 7 may be increased, and measurement points may be set from a greater number of combinations of positions.

As for the focus measuring unit 30 , it is preferable to obtain the difference ΔFZ for each line sensor 17 in consideration of the characteristics of each line sensor 17 . As a result, even if the characteristics of the line sensor 17 vary, the difference ΔFZ can be obtained accurately, and the substrate stage 7 can be driven with high accuracy.

In the present embodiment, the case where the difference ΔFZ obtained for an arbitrary substrate is applied to substrates having the same thickness has been described. good.

The method for manufacturing an article according to the embodiment of the present invention is suitable for manufacturing articles such as devices (semiconductor devices, magnetic storage media, liquid crystal display devices, etc.), color filters, optical components, and MEMS. This manufacturing method includes a step of exposing a substrate coated with a photosensitive agent and a step of developing the exposed photosensitive agent by the exposure method of the embodiment described above using the exposure apparatus 100 . Also, the circuit pattern is formed on the substrate by performing an etching process or an ion implantation process on the substrate using the pattern of the developed photosensitive agent as a mask. By repeating these steps of exposure, development, etching, etc., a circuit pattern consisting of a plurality of layers is formed on the substrate. In the post-process, the substrate on which the circuit pattern is formed is diced (processed), and chip mounting, bonding, and inspection processes are performed. Such manufacturing methods may also include other well-known steps (oxidation, deposition, deposition, doping, planarization, resist stripping, etc.). The method for manufacturing an article according to the present embodiment is advantageous in at least one of performance, quality, productivity and production cost of the article as compared with conventional methods.

Although the preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist. For example, the present invention is applicable not only to a step-and-scan exposure apparatus, but also to a step-and-repeat exposure apparatus (stepper). A measurement method for measuring the surface shape of a substrate including unevenness also constitutes one aspect of the present invention. In such a measurement method, as described above, for each of a plurality of positions in the height direction of the substrate, the position of each measurement point on the substrate in the height direction is measured while moving the substrate in a direction perpendicular to the height direction. get the value. Then, based on the measured values of each measurement point on the substrate, the position of the unevenness existing on the substrate is specified, and the surface shape of the substrate is obtained.

100: exposure apparatus 1: original plate 4: projection optical system 5: substrate 10: control unit 30: focus measurement unit

Claims (20)

An exposure method for exposing the substrate while moving the original and the substrate in a scanning direction,
The substrate is positioned at each of a plurality of positions in the height direction of the substrate, and the substrate is moved in the scanning direction for each of the plurality of positions, and light is directed to each of a plurality of measurement points on the substrate. a first step of obtaining a first measurement value of the position of each measurement point in the height direction by obliquely entering the measurement point;
a second step of determining the surface shape of the substrate based on the first measurement value of each measurement point at each of the plurality of positions acquired in the first step and identifying the positions of unevenness existing on the substrate;
When exposing the substrate, light is obliquely incident on each of the plurality of measurement points while moving the substrate in the scanning direction, and the position of the unevenness specified in the second step is obtained by the measurement unit. a third step of driving the substrate so that the position of the substrate in the height direction becomes a target position based on the second measured value of the position of each measurement point in the height direction;
An exposure method characterized by comprising: 2. The exposure method according to claim 1, wherein said first step acquires said first measurement values corresponding to said plurality of positions in the height direction of said substrate. 3. The method according to claim 1, wherein in the second step, the positions of the unevenness are specified based on the relationship between the first measured value and the plurality of positions in the height direction of the substrate. exposure method. 4. Any one of claims 1 to 3, wherein in the second step, the positions of the unevenness are specified based on differences between the first measured value and the plurality of positions in the height direction of the substrate. 2. The exposure method according to item 1 or 2. For each of the plurality of positions, based on the first measurement value, at each measurement point for correcting a measurement error occurring in the second measurement value due to the position of the unevenness identified in the second step further comprising a fourth step of determining the offset of
In the third step, among the offsets, the second measured value or the target position is corrected by an offset corresponding to the position of the substrate in the height direction when the second measured value was obtained. The exposure method according to any one of claims 1 to 4, wherein 6. The method according to claim 5, wherein in the fourth step, a difference between the first measurement value of each of the measurement points at each of the plurality of positions and each of the plurality of positions is obtained as the offset. exposure method. In the third step, the difference between the second measured value at each measuring point and the offset at each measuring point corresponding to the position of the substrate in the height direction when the second measured value is obtained 7. The exposure method according to claim 5, wherein the substrate is driven so that the position of the substrate in the height direction becomes the target position based on the target position. In the third step, a difference between the target position and each of the measurement points corresponding to the position of the substrate in the height direction when the second measurement value is obtained is set as a new target position, and the second measurement is performed. 7. The exposure method according to claim 5, wherein the substrate is driven so that the position of the substrate in the height direction becomes the new target position based on the value. In the third step, the second measurement value of each measurement point is acquired before each of the plurality of measurement points reaches the exposure position, and the substrate is measured before each measurement point reaches the exposure position. 9. The exposure method according to any one of claims 1 to 8, wherein the substrate is driven so that the position in the height direction becomes the target position. When exposing multiple substrates,
performing the first step, the second step and the third step on the first substrate among the plurality of substrates;
3. The third step is performed using the uneven positions specified in the second step with respect to the first substrate for the substrates other than the first substrate among the plurality of substrates. 10. The exposure method according to any one of 1 to 9. An exposure method for exposing the substrate while moving the original and the substrate in a scanning direction,
The substrate is positioned at each of a plurality of positions in the height direction of the substrate, and the substrate is moved in the scanning direction for each of the plurality of positions, and light is directed to each of a plurality of measurement points on the substrate. obliquely incident to obtain a first measurement value of the position of each measurement point in the height direction;
a second step of determining the surface shape of the substrate based on the first measurement value of each measurement point at each of the plurality of positions acquired in the first step and identifying the positions of unevenness existing on the substrate;
When exposing the substrate, the position of the unevenness specified in the second step, and each measurement point obtained by obliquely entering light at each of the plurality of measurement points while moving the substrate in the scanning direction. a third step of driving the substrate so that the position of the substrate in the height direction becomes a target position based on the second measured value of the position in the height direction of
For each of the plurality of positions, based on the first measurement value, at each measurement point for correcting a measurement error occurring in the second measurement value due to the position of the unevenness identified in the second step a fourth step of determining the offset of
has
In the third step, among the offsets, the second measured value or the target position is corrected by an offset corresponding to the position of the substrate in the height direction when the second measured value was obtained. exposure method. An exposure method for exposing the substrate while moving the original and the substrate in a scanning direction,
The substrate is positioned at each of a plurality of positions in the height direction of the substrate, and the substrate is moved in the scanning direction for each of the plurality of positions, and light is directed to each of a plurality of measurement points on the substrate. obliquely incident to obtain a first measurement value of the position of each measurement point in the height direction;
Based on the difference between the first measurement value of each measurement point at each of the plurality of positions obtained in the first step and the plurality of positions in the height direction of the substrate, the surface shape of the substrate is obtained. a second step of identifying the positions of the unevenness present on the substrate;
When exposing the substrate, the position of the unevenness specified in the second step, and each measurement point obtained by obliquely entering light at each of the plurality of measurement points while moving the substrate in the scanning direction. a third step of driving the substrate so that the position of the substrate in the height direction becomes a target position based on the second measured value of the position in the height direction of
An exposure method characterized by comprising: An exposure apparatus that exposes a substrate while moving the original and the substrate in a scanning direction,
a measurement unit that obliquely impinges light on each of a plurality of measurement points on the substrate and obtains a measurement value of the position of each measurement point in the height direction of the substrate;
a control unit that controls the process of exposing the substrate,
The control unit
The substrate is positioned at each of a plurality of positions in the height direction of the substrate, and the measuring unit measures the plurality of measurement points while moving the substrate in the scanning direction for each of the plurality of positions. to obtain a first measurement value of the position of each measurement point in the height direction,
determining the surface shape of the substrate based on the first measurement value of each measurement point at each of the plurality of acquired positions, and identifying the positions of the unevenness present on the substrate;
When exposing the substrate, the position of the specified unevenness and the height direction of each measurement point obtained by measuring the plurality of measurement points with the measurement unit while moving the substrate in the scanning direction and a second measurement value of the position, driving the substrate so that the position of the substrate in the height direction becomes a target position. The control unit, for each of the plurality of positions, based on the first measurement value, offsets at each measurement point for correcting a measurement error that occurs in the second measurement value due to the position of the unevenness. seeking
14. The method according to claim 13 , wherein, among the offsets, the offset corresponding to the position of the substrate in the height direction when the second measured value is obtained is used to correct the second measured value or the target position. The described exposure apparatus. The measurement unit includes a plurality of sensors that detect light reflected by each of the plurality of measurement points,
15. An exposure apparatus according to claim 14 , wherein said offset is obtained for each of said plurality of sensors. An exposure apparatus that exposes a substrate while moving the original and the substrate in a scanning direction,
a measurement unit that obliquely impinges light on each of a plurality of measurement points on the substrate and obtains a measurement value of the position of each measurement point in the height direction of the substrate;
a control unit that controls the process of exposing the substrate,
The control unit
The substrate is positioned at each of a plurality of positions in the height direction of the substrate, and the measuring unit measures the plurality of measurement points while moving the substrate in the scanning direction for each of the plurality of positions. to obtain a first measurement value of the position of each measurement point in the height direction,
determining the surface shape of the substrate based on the first measurement value of each measurement point at each of the plurality of acquired positions, and identifying the positions of the unevenness present on the substrate;
When exposing the substrate, the position of the specified unevenness and the height direction of each measurement point obtained by measuring the plurality of measurement points with the measurement unit while moving the substrate in the scanning direction driving the substrate so that the position of the substrate in the height direction is a target position based on the second measured value of the position;
For each of the plurality of positions, based on the first measurement value, obtain an offset at each measurement point for correcting a measurement error that occurs in the second measurement value due to the identified position of the unevenness,
When driving the substrate so that the position of the substrate in the height direction becomes a target position, the offset corresponds to the position of the substrate in the height direction when the second measurement value is obtained. and correcting the second measurement value or the target position with an offset. An exposure apparatus that exposes a substrate while moving the original and the substrate in a scanning direction,
a measurement unit that obliquely impinges light on each of a plurality of measurement points on the substrate and obtains a measurement value of the position of each measurement point in the height direction of the substrate;
a control unit that controls the process of exposing the substrate,
The control unit
The substrate is positioned at each of a plurality of positions in the height direction of the substrate, and the measuring unit measures the plurality of measurement points while moving the substrate in the scanning direction for each of the plurality of positions. to obtain a first measurement value of the position of each measurement point in the height direction,
A surface shape of the substrate is obtained based on a difference between a first measurement value of each measurement point at each of the plurality of acquired positions and the plurality of positions in the height direction of the substrate, and unevenness existing on the substrate is determined. locate the
When exposing the substrate, the position of the specified unevenness and the height direction of each measurement point obtained by measuring the plurality of measurement points with the measurement unit while moving the substrate in the scanning direction and a second measurement value of the position, driving the substrate so that the position of the substrate in the height direction becomes a target position. exposing a substrate using the exposure apparatus according to any one of claims 13 to 17 ;
developing the exposed substrate;
producing an article from the developed substrate;
A method for manufacturing an article, comprising: A measurement method for measuring a surface shape of a substrate including unevenness,
The substrate is positioned at each of a plurality of positions in the height direction of the substrate, and a plurality of measurements on the substrate are performed at each of the plurality of positions while moving the substrate in a direction orthogonal to the height direction. a first step of obtaining a first measurement value of the position of each measurement point in the height direction by obliquely incident light on each point;
a second step of determining the surface shape of the substrate by specifying the position of the unevenness based on the first measurement value of each measurement point at each of the plurality of positions acquired in the first step;
Each measurement obtained by the measurement unit by obliquely entering light into each of the plurality of measurement points while moving the substrate in a direction perpendicular to the height direction and the position of the unevenness specified in the second step. a third step of driving the substrate so that the position of the substrate in the height direction becomes a target position based on a second measurement value of the position of the point in the height direction;
A measuring method characterized by having A measurement method for measuring a surface shape of a substrate including unevenness,
The substrate is positioned at each of a plurality of positions in the height direction of the substrate, and a plurality of measurements on the substrate are performed at each of the plurality of positions while moving the substrate in a direction perpendicular to the height direction. a first step of obtaining a first measurement value of the position of each measurement point in the height direction by obliquely incident light on each point;
Based on the difference between the first measurement value of each measurement point at each of the plurality of positions acquired in the first step and the plurality of positions in the height direction of the substrate, the position of the unevenness is specified and the a second step of determining the surface shape of the substrate;
A measuring method characterized by having

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